1. Field of the Invention
The present invention relates to differential amplifiers and, more particularly, to a differential amplifier with high-speed common mode feedback.
2. Description of the Related Art
A differential amplifier is a well-known circuit that amplifies a differential input signal. Differential amplifiers are used in many applications, and have a number of advantages, such as immunity to supply noise and two times higher dynamic range compared to a single-ended amplifier. In one application, a differential amplifier is used in a switched capacitor circuit.
One problem with amplifying the output of a switched capacitor circuit is that there are many switches opening and closing, and these opening and closing switches can cause strong and abrupt glitches in the output where, for example, a logic high signal drops momentarily to a logic low signal. The glitches introduce a common mode component into the signal output from the switched capacitor circuit which can substantially limit the capability of the differential amplifier. As a result, there is a need for a differential amplifier that can reduce the effect of glitches in the signals output from a switched capacitor circuit.